Tourniquets are well-known devices for applying pressure to an appendage or extremity to limit the flow of arterial blood therethrough. They have been used as a "first aid" treatment of hemorrhaging limbs and also as means for creating ischemia in a surgical field. Although the present invention could be used as a "first aid" method and apparatus, the following discussion will focus primarily on surgical applications for the sake of brevity.
Tourniquets are used during surgery of the extremities so that procedures may be performed in a bloodless surgical field. Typically, a tourniquet is applied to a proximal portion of an extremity to limit blood flow to a distal portion of an extremity. For example, a tourniquet is often wrapped about the proximal portion of a finger which is to be operated on near its distal tip.
An early technique involved wrapping a rubber bandage, known as an Esmarch bandage, tightly around an extremity to exsanguinate the blood and to cut off the circulation. The pressure created by an Esmarch bandage can be very great, and this method has largely been abandoned in favor of carefully monitored pneumatic tourniquets since the excessive pressure associated with the improper use of an Esmarch bandage has been known to damage delicate neuronal tissue, resulting in neuropraxia and pain. The present invention is directed to such pneumatic tourniquets, and more generally to fluid-operated tourniquets, wherein pressurized fluid causes a cuff to circumferentially compress an extremity. The cuff fluid can be any liquid or gas or combination thereof, but the present discussion will be directed primarily to pneumatic embodiments.
While a number of pneumatic cuffs and inflation systems are available for use on arms and legs, application of these devices on the distal parts of extremities, i.e. wrists, ankles, fingers, and toes, is generally not feasible. Moreover, some current surgical tourniquet systems lack ease of portability and thus are found in operating rooms but are not available in emergency rooms and clinics. As a result, surgery on an isolated finger, for example, is usually accomplished with application of an Esmarch bandage type of tourniquet, often a makeshift piece of rubber capable of creating excessive pressure and irreversible damage to nerves and vessels.
In addition, prior art pneumatic tourniquet systems generally fail to include a mechanism for compensating for increases or decreases in cuff air pressure. A decrease in the air pressure can be caused by a slow leak, for example.
The present invention is directed to the problems addressed above. In particular, the present invention includes an apparatus for limiting blood flow through an extremity which includes means for safely limiting the fluid pressure within the cuff. In addition, the pressure limiting means preferably serves to substantially maintain the preset pressure within the cuff in the event of a slow leak, for example. Finally, preferred embodiments of the apparatus of the present invention are portable and inexpensive, making them practical for operating room, emergency room and clinical use.